Author + information
- Received August 11, 2011
- Revision received November 26, 2011
- Accepted December 15, 2011
- Published online April 3, 2012.
- Alexandra H. Smith, MSc⁎,
- Michael A. Kuliszewski, BSc⁎,
- Christine Liao, BSc⁎,
- Dmitriy Rudenko, BSc⁎,
- Duncan J. Stewart, MD† and
- Howard Leong-Poi, MD⁎,⁎ ()
- ↵⁎Reprint requests and correspondence:
Dr. Howard Leong-Poi, 6-044 Queen Wing, St. Michael's Hospital, 30 Bond Street, Toronto, Ontario M5B 1W8, Canada
Objectives The aim of this study was to compare temporally separated vascular endothelial growth factor (VEGF) and angiopoietin (Ang)-1 delivery with concomitant delivery or single VEGF delivery, for therapeutic angiogenesis in chronic ischemia.
Background Single gene delivery of VEGF results in immature neovessels that ultimately regress. Endogenously, VEGF acts early to initiate angiogenesis, whereas Ang-1 acts later to induce vessel maturation. Timing VEGF and Ang-1 gene delivery to mimic endogenous angiogenesis might be more effective for sustained neovascularization.
Methods Unilateral hindlimb ischemia was induced in 170 rats. Ultrasound-mediated gene delivery was performed with cationic microbubbles and plasmid deoxyribonucleic acid. Groups included VEGF at 2 weeks, VEGF/Ang-1 at 2 weeks, VEGF at 2 weeks with Ang-1 at 4 weeks, and untreated control subjects. At 2, 4, and 8 weeks after ligation, blood flow and flow reserve (FR) were assessed by contrast-enhanced ultrasound. Vascular density, organization, and supporting cell coverage were assessed by fluorescent microangiography and immunohistochemistry.
Results In untreated control subjects, blood flow, FR, and vessel density remained reduced. The VEGF delivery improved flow and vessel density at 4 weeks; however, FR remained low, supporting cell coverage was poor, and flow and vessel density regressed by 8 weeks. The VEGF/Ang-1 co-delivery marginally increased flow and vessel density; however, FR and supporting cell coverage improved. After temporally separated VEGF and Ang-1 delivery, blood flow, vessel density, and FR increased and were sustained, with improved pericyte coverage at 8 weeks.
Conclusions In conclusion, temporally separated VEGF and Ang-1 gene therapy results in sustained and functional neovascularization.
This work was supported by an Operating Grant (MOP 62763) from the Canadian Institutes of Health Research, Ottawa, Ontario, Canada, and an Equipment Grant from the Canadian Foundation for Innovation, Ottawa, Ontario, Canada. Dr. Leong-Poi is supported by a Clinician Scientist Phase II Award from the Heart and Stroke Foundation of Ontario, Ottawa, Ontario, Canada, and an Early Researcher Award from the Ministry of Research and Innovation, Ontario, Canada. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- Received August 11, 2011.
- Revision received November 26, 2011.
- Accepted December 15, 2011.
- American College of Cardiology Foundation